Well in the US with its altimetry, the controller has QNHs for the airports in the area and it is transmitted upon initial contact, if operating below FL180. The QNH is given with the descent clearance below TA/TL for the area. Yes, controllers forget and pilots ask, so its not perfect, but FL180 gives everyone time to straighten it out. VFR pilots are responsible to periodically get a QNH, how well that works I'm not prepared to say.
Usually on the hand-off to arrival control, you'll get a QNH for that airport. For the crew, it works because you can do the approach/in-range check early enough for the altimeters to be set prior to getting vectors or prior to the IAF.
I was an Eastern Airlines (dearly missed) and we used QFE almost to the end and had all sorts of peculiar altimetry procedures using QFE on the main altimeters and QNH on third altimeter. We both had to refer to the third when being vectored and change over to the mains for the actual approach.
There is nothing sacred about FL180, but, as a pilot, I like the idea of being on QNH once I've descended below the highest terrain.